Production of fibrous logs by continuously passing slurry through a forming chamber

ABSTRACT

Methods and apparatus for continuous manufacture of combustible simulated logs from paper or similar material. A slurry of water and combustible solids is continuously supplied forcibly into one end of a forming chamber provided with a plurality of radial drainage holes arranged in hole groups spaced from each other, each of the hole groups having a mean center axially spaced from each other by exponentially decreasing distances in the downstream direction whereby the solids become progressively compacted as the water drains through the holes. The compacted solids continuously exit from the forming chamber through a nonperforated region thereof for providing frictional resistance to movement of the formed andcompacted log whereby a coacting back pressure is maintained within the forming chamber for causing the slurry to reside within the forming chamber at the region of the drainage holes during the period of time and in the manner required for continuous drainage and compaction to occur. A cylindrical inner tube concentric with the forming chamber is disclosed for providing a log with a central longitudinal hole therethrough.

United States Patent US. Cl. 162-293 8 Claims ABSTRACT OF THE DISCLOSURE Methods and apparatus for continuous manufacture of combustible simulated logs from paper or similar material. A slurry of water and combustible solids is continuously supplied forcibly into one end of a forming chamber provided with a plurality of radial drainage holes arranged in hole groups spaced from each other, each of the hole groups having a mean center axially spaced from each other by exponentially decreasing distances in the downstream direction whereby the solids become progressively compacted as the water drains through the holes. The compacted solids continuously exit from the forming chamber through a nonperforated region thereof for providing frictional resistance to movement of the formed and compacted log whereby a coacting back pressure is maintained within the forming chamber for causing the slurry to reside within the forming chamber at the region of the drainage holes during the period of time and in the manner required for continuous drainage and compaction to occur. A cylindrical inner tube concentric with the forming chamber is disclosed for providing a log with a central longitudinal hole therethrough.

CROSS REFERENCE This application is a continuation of co-pending US. patent application Ser. No. 880,474, filed Dec. 9, 1969 (now abandoned) which was a continuation of then copending US. patent application Ser. No. 569,958, filed Aug. 3, 1966 (now abandoned).

The present invention relates to the manufacture of combustible products from paper or similar material and, more particularly, to such products in the form of a generally simulated log and to methods and apparatus for making same.

Heretofore, it has been customary to manufacture products in the form of simulated logs or brickets from wood shavings, sawdust, waste paper or the like, such as newspaper and other organic base materials having desirable properties of combustion for both heat and light, primarily intended for use in a fireplace as a substitute for a log or in barbecue pits or appliances for similar purposes. While previous products have met with varying degrees of commercial success, numerous problems and difiiculties have been encountered which have mitigated their general utility, convenience, economy and availability. For example, products composed of wood or primarily thereof have required that their manufacture be performed at or near specific locations, such as sawmills, where the raw materials are available in the form of waste without the necessity of transportation of the raw material for uneconomically excessive distances, such being the case for otherwise generally successful simulated log products such as, for example, Presto-Logs. In addition, such log products utilizing Wood chips or other relice atively large intrinsic pieces of base material require' relatively high compressive forces in the molding process of manufacture as well as binding materials and/or agents which add to the cost of manufacture as well as generally detracting from the initial combustibility of the product. While compressed wood groducts composed primarily of sawdust or other finely ground or granulated wood materials have relatively improved initial combustion characteristics, the relatively high initial combustion rate similarly continues with consequently decreased combustion duration for the entire product.

Primarily for the foregoing reasons, various attempts have been made in the past to provide simulated logs or log portions made from paper or similar carbonaceous materials which are widespread and generally available as raw materials in the form of waste in general proportion to the population and, accordingly, in proportion to the available and potential market for the simulated log products. However, unlike wood products, which normally contain sap or else can be relatively readily treated in bulk so as to have a sufiiciently viscid characteristic to provide for adhesion and cohesion of the material when compressed, even extreme compression pressures do not provide an adequate bond for dry paper materials and, due to the nature of such materials even when shredded or nodulated or otherwise configured, do not lend themselves well for treatment purely by a binding agent. Various attempts in the past to employ wet paper and squeeze out the water by compression in a drainage mold have been unsuccessful from an economic standpoint and have resulted in a non-uniform product for various reasons.

Therefore, it is one of the objects of the present invention to provide a combustible product in a cylindrical form simulating that of a log and composed of readily available scrap paper and various other carbonaceous materials such as particles or nodules of coal, and, in its preferred form, having a configuration for facilitating ignition and combustion.

Another object of the present invention is the provision of a method for manufacturing such a product in a continuous manner from a slurry of water and combustible solids for eliminating the expense and inconvenience of making such a product in an essentially individual or batch method While obtaining a uniform and readily handled product.

Another object of the present invention is the provision of apparatus for making a combustible product from a slurry of water and combustible solids, preferably scrap paper and coal particles, wherein the product is continuously formed in an effectively endless manner for speed of manufacture and uniformity of product.

According to the present invention, there is provided a combustible product in a cylindrical form simulating that of a log and composed of combustible solids preferably comprising scrap paper in initially shredded form or other carbonaceous material of a fibrous nature, preferably in combination with coal particles. In a preferred embodiment, the log product is provided with a central bore hole for facilitating both the forming manufacture of the product itself and various desirable subsequent treatment and handling procedures, such as steam drying or evaporative drying as well as impregnation by paraffin and/or other flammable materials for aiding ignition and subsequent combustion.

According to the method of the present invention, a combustible product is made from a slurry of water and combustible solids by continuously forcibly supplying such slurry under pressure into one end of a forming chamber, continuously draining such liquid from the forming chamber to cause the remaining solids to compact, and continuously permitting such compacted solids to be forced out of the other end of the forming chamber.

In a preferred embodiment of apparatus in accordance with the present invention for performing the manufacture of the aforesaid preferred product, there is provided forming chamber means comprising a cylindrical outer forming tube and a cylindrical inner forming tube concentric therewith, both tubes having a plurality of radial drainage holes through the tube walls for drainage of the slurry water during forming and compaction of the product. Preferably, such holes are arranged and disposed relative to each other and in accordance with the slurry input pressure in a manner and pattern herein denominated as exponential whereby the rate of drainage of the water is believed to be continuously related to the rate of product formation and compaction within the forming chamber. A downstream region of the forming chamber means is provided for creating and maintaining frictional resistance to movement of the formed and compacted wet product therethrough whereby an effective degree of back pressure is maintained within the forming chamber for causing the slurry to reside within the forming chamber at the region of the drainage holes during the period of time and in the manner required for drainage and compaction to occur.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view, partly diagrammatic, of a preferred embodiment of apparatus in accordance with the present invention for practicing the preferred method of the present invention;

FIG. 2 is a perspective view, partly broken away and sectioned, of a simulated log product in accordance with the present invention manufactured by the preferred apparatus and method of FIG. 1;

FIG. 3 is an enlarged fragmentary side elevation view, partly broken away and longitudinally sectioned, illustrating the forming chamber portion of the apparatus shown in FIG. 1;

FIG. 4 is a fragmentary enlarged view of a developed section of the outer cylinder defining the forming chamber of FIG. 3, showing the relationship of the water drainage holes in accordance with the parameters of a particular embodiment of apparatus in accordance with the present invention; and

FIG. 5 is a reduced size fragmentary longitudinally sectioned view, partly in elevation, of the forming chamber, illustrating the log product forming action therein.

Referring to the drawings, and particularly to FIG. 1 initially, there is generally indicated a supply means at which may comprise a hopper into which is continuously delivered a slurry of water, paper and other combustible solids such as particles of coal and any other ingredients which may be desired for specific purposes such as, for example, color of the log 12 either before or during combustion thereof, spark effects and so forth, although such ancillary effects are preferably obtained by addition to the log in the form of coating and/or impregnation as herein described. The paper is prepared as by shredding, tearing, grinding and/or any other convenient means of reducing the paper to an irregular and non-compacted form. Such ingredients preparation may include the mixing of the paper with water in any convenient manner, although such mixing operation preferably takes place within the supply means 10 as by rotary, tumbling, surging or other mixing operations so that the ingredients become fairly uniformly intermixed, uniformity of mix of the slurry being desirable for general considerations but not being essential or critical in view of the nature of the process as hereafter described.

The slurry is supplied via a conduit 14 to a pressure feed means, indicated generally at 16, which preferably comprises a pump apparatus (such as Model H-25 Hydropulse Pump, rated at 25 gallons per minute at 700 p.s.i., manufacture dby De Laval Turbine Inc. of Trenton, N .J having a plurality of continually alternately pulsing pressure units 18 operating in effectively continuous supply of the slurry to an input conduit 20 for introduction into the forming chamber means 22, the latter being suitably provided with a drain conduit 24 for carrying the emitted drain water from the forming chamber means 22 to a drain area indicated generally at 26. Recirculation means (not shown) carries the drain water back to the supply means 10 for mixing reuse. The continuously formed product evolving from the forming chamber means 22 is supported on a suitable platform means 28, and a suitable cutter means 30 transversely slices the continuous product 32 by a blade means 34 to cause separation into desired lengths of discrete wet log products, as indicated at 12.

Referring to FIG. 2, there is seen a final simulated log product 36 in accordance with the present invention having a generally cylindrical outer configuration and provided with a central longitudinal bore hole 38 therethrough, both the exterior surface 40 and the interior surface 42 having a generally roughened surface appearance in spite of the addition of paralfin or other combustion aiding ingredients added by coating or impregnation techniques, as described more completely elsewhere herein.

Referring to FIG. 3 in conjunction with FIG 1 for a more detailed description of a specific embodiment of the forming chamber portion 22 of the apparatus shown in FIG. 1, the forming chamber means is seen to comprise a cylindrical outer forming tube 44 suitably provided with an annular flange 46 bolted as at 48 to a similarly provided flange 50 on the input conduit 20. A cylindrical inner core forming tube 52 is disposed coaxially within the outer tube 44 and substantially coterminuously therewith. A drain manifold 54 is disposed concentrically about the outer tube 44 in preferably sealed engagement therewith except for the drain conduit 24 leading therefrom. The inner tube 52 is similarly provided with a drain conduit 56 at its front end 58, the inner core tube drain conduit 56 being coupled in any convenient manner (not shown) to either the outer drain conduit 24 or directly to the return drain 26, it being desirable that the inner core drain conduit 56 be disposed in a manner such as not to interfere with the flow of the slurry and the forming action within the forming chamber itself. The rear or downstream end 60 of the inner core tube 52 is closed and may reside at the illustrated location relative to the open rear end 62 of the outer forming tube 44 or may project rearwardly therefrom as desired in accordance with the frictional parameter of operation or for axially supporting the formed log product 32 as it leaves the forming chamber means 22. The inner core forming tube 52 is provided with a plurality of core drainage holes indicated generally at 64 while the outer forming tube 44 similarly is provided with a plurality of peripheral drainage holes indicated generally at 66. While the exact nature, disposition and relative location of the individual holes as well as the sets of holes 64 and 66 with respect to each other as well as relative to their log forming function in the specific embodiment illustrated will be described in more detail hereinafter, it may be noted that a stream direction is defined by the slurry input direction and the formed wet product output direction indicated by the respective arrows 68 and 70, and all of the drain holes in hole sets 64 and 66 in the specific embodiment illustrated reside upstream from a plane indicated by phantom plane line 72 representative of an imaginary geometric plane diametric to both the outer and inner tubes 44 and 52 and located tangentially to the most downstream edge of any of the holes in the hole sets 64 and 66. Similarly, numeral 74 designates a diametric plane at the upstream extremus of the hole sets 64 and 66. Since, as can be readily appreciated, primary water removal by means of drainage within the illustrated apparatus (as distinguished from secondary Water removal by means of evaporation or other drying means during any subsequent operations) can only be accomplished between the planes 74 and 72, the region designated generally at 76 for convenience of reference is herein defined as the primary forming chamber and is defined by the planes 74 and 72, the interior wall surface 78 of the outer forming tube 44 and the exterior wall surface 80 of the inner core forming tube 52 in the illustrated embodiment.

Referring to FIGS. 3 and 4, there will be described the hole arrangement in the specifific illustrated embodiment of the forming chamber as employed in an actual working unit under specific conditions. The parameters of structure and operation will be discussed thereafter.

The outer forming tube 44 is 17 /2" long and has an outer diameter of 4%" with a wall thickness of Vs". The inner core forming tube 52 is approximately 16% long within the forming chamber, has an outer diameter of 1" and a wall thickness of /8". All of the holes of hole sets 64 and 66 are disposed in annular rows for convenience and are formed by radially drilling holes of 7 diameter through their respective tubes 52 and 44. In the specific pattern more clearly shown in the developed view of FIG. 4, the set of holes 66 consists of nine annular rows of holes, the first or extreme upstream row being indicated at 84 and the last or extreme downstream row being indicated at 86, such indications being by means of phantom lines through the row hole centers. The second eighth rows of holes reside therebet'ween in ascending numerical order from the upstream side, and all longitudinal distances are measured from hole centers. The second row is A downstream from the first row at 84, the third row is 1%" from the second row, the fourth row is /2" from the third row, and each of the succeeding downstream rows is A" from its adjacent row. The first and second rows each contain 28 holes, the third row contains 60 holes, the fourth seventh rows each contains 28 holes, the eighth row contains 56 holes, and the last row 86 contains 60 holes, all of the holes being circumferentially equispaced within their respective rows. The last row 86 is /8" from the end 62 of the outer forming tube 44.

In the inner core forming tube 52, there are six annular rows of holes 64, all of the rows being equispaced A from each other and each containing -15 circumferentially equispaced holes. In relative location, the first or extreme upstream row of holes in the inner core forming tube 52 is designated in FIG. 3 at 88 and resides in the same diametric plane as the third hole row 90 of the outer forming tube 44.

Using a slurry composed of about by weight of shredded scrap newsprint in water, and a slurry input pressure of about 500 p.s.i., the above-described forming chamber means 22 has consistently produced a wet product log portion 12, with an average length of 16", wet weight of 6 pounds, and solids content of 2 /2 pounds, in an average forming time of about 45 seconds. The same results have been consistently produced with the slurry composed of about 10% by weight of shredded scrap newsprint and coal particles in water, the coal being about 64-mesh, and the ratio of paper to coal being about 4:1 by weight. The foregoing data are exemplary only and, while indicative of a satisfactory and operative mode in accordance with the present invention, variations of the data in accordance with variations in the structural and operationl parameters will become obvious to those skilled in the art, particularly after an understanding of such parameters is obtained by further study of the hereinafter discussion pertaining to the actual and theoretical effects of parametric variations.

In describing the operation of the illustrated apparatus, reference is made to FIG. 5 in conjunction with the previously described drawings. In commencing operation, a mechanical plug, indicated generally in phantom at 92 in FIG. 3, is disposed within the outer forming tube 44 and about the inner core forming tube 52 in relatively watertight engagement therewith and inserted to a position indicated at 92 which is upstream from the primary forming chamber 76. Then the slurry 94 is supplied under pressure in the direction of arrow 68 and the plug 92 is restrainedly permitted to withdraw in a downstream direction, the plug 92 gradually passing through the primary forming chamber 76 at a rate commensurate with the sequentially occurring drainage of water out through the drainage holes 66 and 64 so that formation of the product occurs with increasing compaction as the plug 92 progresses past the holes 66 and 64. Such progressively increasing compaction formation of the product arises due to the combined effects of slurry input pressure and water drainage, i.e., the slurry pressure causes the water to be forced out of the forming chamber 76 through the holes 66 and 64, causing a progressively increased proportion of solids content per unit volume in the forming mix 96 (FIG. 5) so that the solids become more intimately intermixed and associated with each other in a sufficiently random manner to obtain maximal interconnection and binding therebetween while pressure is maintained so that such intimately associated solids become progressively compressed and compacted into the final cylindrical form of wet product 32. Formation effectively commences at the upstream terminus plane 74 of the primary forming chamber 76, and effectively ceases at the downstream terminus plane 72. As the plug 92 is withdrawn from the primary forming chamber 76, it enters a chamber region indicated generally at 98 defined by the interior wall surface portion 100 of the outer forming tube 44 between the downstream plane 72 and the tube end 62, such wall portion 100 being denominated herein as resistance means. As the wet product 32 enters the chamber region 98, the frictional engagement of its circumferential periphery with the resistance means 100 gradually increases with continued withdrawal of the mechanical plug 92 until the plug 92 is completely with drawn and the wet product 32 is in frictional contact with the entire resistance means 100. Thereafter, the continuously moving wet product 32 within the downstream chamber region 98 effectively constitutes a mechanical plug having that amount of resistance to downsream movement necessary to maintain the progressively forming product mix 96 within the primary forming chamber 76 for the desired amount of drainage and compaction time while permitting continuous mass movement in the downstream direction as such forming and compaction occurs. It should be noted that the circumferential surface portion of the inner core forming tube 52 residing downstream of plane 72 also contributes to the frictional resistance to movement of the wet product 32 and, to the extent such contribution occurs, is included within the term resistance means.

Regarding the set of holes 66 in the outer forming tube 44, it should be noted that they are arranged in a pattern which is basically exponential with regard to their longitudinally spaced locations. Such relationship becomes clearer upon noting that the nine hole rows from 84 to 86 are grouped exponentially, although such groupings are not precise in the actual embodiment illustrated due to tooling limitations in their disposition. Thus, it is noted that the first hole row 84 and is downsream adjacent hole row constitute a first group of drainage holes, the third hole row constitutes a second downstream group of drainage holes, and subsequent downstream groups of holes are composed of the fourth and fifth, sixth and seventh, eighth and ninth 86 hole rows, each such hole group containing approximately the same number of holes. The effective longitudinal mean centers of the aforesaid hole groups are longitudinally exponentially displaced relative to each other, taking into account the longitudinally dispersed displacement of the holes within each of the groups so that even the effective mean center of each such group is longitudinally exponentially displaced from its linearly measured physical center.

It should be noted that the pattern of the drainage holes 64 in the inner core forming tube 52 is that of uniform distribution in the specific embodiment illustrated and that such set of holes 64 is disposed physically opposite only the third to eighth rows of holes 66 in the outer forming tube 44. However, the amount of drainage action through the inner core holes 64, coupled with the nature of the wet formed product, indicates that effectively exponential action takes place therethrough as well.

While experimentation with both randomly and uni formly distributed holes 66 has produced a usable product, the most consistent results in terms of uniformity of density and distribution of solids in the product, as well as continuity of product formation, have been achieved with the foregoing described forming chamber means.

In order to aid those skilled in the art to understand the present invention more clearly, the following comments are presented relative to structural and operational parameters, based primarily on theoretical considerations but supported at least partially in many instances by observation of experimental and test conditions and results. For any given set of drainage holes, it appears that the slurry input pressure should be maintained at a constant value in order to acquire a final wet product log 12 of uniform distribution and density. concomitantly, when the input pressure is maintained constant, any given set of holes will produce a log of a particular density. In order to achieve higher density, more drainage holes should be added downstream of the plane 72 to obtain greater drainage. For a lower density with the same set of holes, more slurry input pressure is applied so as to force the contents through the forming chamber 76 at a faster rate such that the water does not have sufficient time to adequately drain out through the drainage holes even though the increased pressure causes a faster drainage flow. It should be noted, however, that density does not appear to be inversely proportional to input pressure and, further, that excessive input pressure causes the formed log product 32 to have a tendency to effectively explode or, at least, disintegrate into fragments and sections due to expansion when the product comes out of the chamber end 62. Conversely, with any given set of holes, a lower limitation on pressure for creating a less dense product occurs when the pressure is so low that mass movement is too slow whereby excessive rather than less drainage occurs, and such effects occur in a manner such that the product commences forming as at 96 but upstream of the plane 74 because the formed product 32 is not moving as fast as the occurrence of the drainage; in such event, nonuniform density occurs because of alternate plugging and unplugging as the product is partially formed upstream and then is forced by the input pressure to rapidly pass downstream. In other words, with too little pressure, the compaction face appears to move upstream above plane 74 into the non-holed portion of the outer forming tube 44 and then pulsing occurs and causes the thus partially formed product to dislodge intermittently, with the result that final product 32 does not have coherence. On the other hand, excessive pressure appears to cause the initial compaction face to move downstream from the plane 74 into the forming chamber 76 and then the product is watery and soft. It appears that a continuous wet product 32 of a given density can be formed at a faster rate by increasing the drainage during the initial portion of the product formation, i.e., by adding additional drainage holes 66 upstream of the plane 74 at the next exponential level, coupled with the application of increased slurry input pressure. Since the pressure is greater and therefore the partially formed product and slurry mass 96 is moving faster through the principal drainage portion of the primary forming chamber 76, it appears that an increased number of drainage holes is required at the downstream end of the forming chamber.

It may be noted that drainage holes of diameter have been found to provide optimum results. Holes of smaller diameter appear to unduly restrict the flow of water due primarily to interference by the solids, while holes of larger diameter appear to permit both passage of and blocking by the solids. However, it will be understood that variations in hole diameters are permissible, largely dependent on the consistency and nature of the solids and the pressures employed, as will be clear to those skilled in the art.

Final handling and treatment of the wet product log 12 to obtain the final product log 36 may include steam and/or radiant heating to obtain effectively evaporative drying of the wet product 12 for elimination of its water content. Thereafter, it is preferred to both impregnate and coat the product with parafin or the like by merely a dip ping process. It has been found that, in addition to the final products ornamental design which is attractive and pleasing in appearance, mechanical handling during production is facilitated by the axial hole 38 in that the wet log 12 dries faster under conditions of steam pressure drying or evaporative drying or both such drying methods sequentially, and the dried log is more easily and rapidly penetrated and impregnated by paraffin by merely a dip process because of both the larger combined surface area and the fact that penetration occurs in both radial directions, i.e., from the outer surface 40 inwardly and the inner surface 42 outwardly. Still further, the overall weight of the log 36 is reduced while both maintaining and creating a large burning surface area. As combustion progresses, ignition of the coal particles 102 occurs and the burning thereof appears to enhance both the light and heat effects. Importantly, both ignition and combustion are facilitated by the central ventilation through the bore hole 38. Perhaps most importantly, a log 36 of the illustrated configuration has improved uniformity of density as well as distribution of its combustible ingredients due to the nature of the forming process employed.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Apparatus for making a combustible product from a slurry of liquid and combustible solids, comprising:

a cylindrical tube having an input end and a forming portion;

slurry input means for continuously forcing said slurry under pressure into said forming portion; said forming portion having a plurality of radial liquid drainage holes, spaced in substantial uniformity circumferentially, and located in hole groups spaced from each other, each of said hole groups having an effective mean center in the axial direction of flow of said slurry, said mean centers of said hole groups being axially spaced from each other by exponentially decreasing distances in the downstream direction so that, as the slurry progresses through said forming portion, such liquid is progressively drained therefrom through said holes for progressively increasing the compaction of such solids flowing axially through the forming portion; and

means for tending to resist passage of such compacted mass of solids out of said forming portion so that the solids become compacted coherently for producing a coherent final product.

2. The apparatus of claim 1 in cluding a cylindrical inner tube disposed coaxially within said first-mentioned tube whereby said final product has an axial bore.

3. The apparatus of claim 2 wherein said slurry input means uninterruptedly forces said slurry into said forming portion at a substantially constant pressure and rate.

4. The apparatus of claim 1 wherein said means for tending to resist consists of a cylindrical non-perforated coaxial integral wall portion of said tube downstream from said forming portion and having a diameter idenucal therewith.

5. The apparatus of claim 4 including a cylindrical inner tube disposed coaxially within said first-mentioned tube whereby said final product has an axial bore.

6. The apparatus of claim 1 wherein said slurry input means uninterruptedly forces said slurry into said forming portion at a substantially constant pressure and rate.

7. The apparatus of claim 6 wherein said means for tending to resist consists of a cylindrical non-perforated coaxial integral wall portion of 10 said tube downstream from said forming portion and having a diameter identical therewith. 8. The apparatus of claim 7 including a cylindrical inner tube disposed coaxially within said 5 first-mentioned tube whereby said final product has an axial bore.

References Cited UNITED STATES PATENTS 2,969,836 1/1961 Ceriat 162-293 X 1,079,774 11/1913 Lappen 162--406 3,021,254 2/1962 Helversen et a1. 162-406 X S. LEON BASHORE, PrimaryExaminer R. H. TUSHIN, Assistant Examiner U.S. Cl. X.R. 

